I'm on Instagram and have a bunch of followers, around 200K.
SO - My plan is to squat as the IG users pick up Threads. Most people will just follow the same people from IG (Meta encourages it and it fills your feed fast).
My follower count on Threads should grow just from that alone, right?
THEN - Facebook finally federates, right?
THEN! Facebook allows for account migration to Mastodon.
I would wait with your master plan, until you know that Meta allows you to move your account to Mastodon. Oh yeah, and you should use a burner phone without any personal data (medical history, contacts, location, financial information, whatever "sensitive information" is, etc.) when you install the app.